CT600 Box 440: Corporation Tax Payable Explained
Box 440 shows the total Corporation Tax payable by your company for the accounting period. This is the headline figure that determines how much you owe HMRC.
What Is Box 440?
Box 440 is labelled: "Corporation Tax chargeable"
This is the tax calculated on your company's profits after applying:
- The appropriate tax rate(s)
- Marginal relief (if applicable)
- Any special rates for ring-fence profits
Current Corporation Tax Rates
Since April 2023, Corporation Tax rates depend on your profit level:
| Profit Level | Tax Rate | Description |
|---|---|---|
| Under £50,000 | 19% | Small profits rate |
| £50,000 - £250,000 | 19% - 25% | Marginal relief applies |
| Over £250,000 | 25% | Main rate |
How Box 440 Is Calculated
Simple Case: Under £50,000 Profit
If your taxable profits are below £50,000:
``` Taxable profits × 19% = Box 440 ```
Example:
- Taxable profits: £40,000
- Tax rate: 19%
- Box 440: £7,600
With Marginal Relief: £50,000 - £250,000
If profits are in the marginal band, you pay 25% minus relief:
``` Tax at 25% - Marginal Relief = Box 440 ```
Marginal relief formula: ``` 3/200 × (Upper limit - Profits) × (Profits ÷ Augmented profits) ```
Example:
- Taxable profits: £100,000
- No associated companies
- Tax at 25%: £25,000
- Marginal relief: £2,250
- Box 440: £22,750
Simple Case: Over £250,000 Profit
If your taxable profits exceed £250,000:
``` Taxable profits × 25% = Box 440 ```
Example:
- Taxable profits: £300,000
- Tax rate: 25%
- Box 440: £75,000
Detailed Calculation Example
Full Calculation with Marginal Relief
Company with £150,000 profit, no associated companies:
| Step | Calculation | Amount |
|---|---|---|
| 1. Taxable profits | Box 410 | £150,000 |
| 2. Tax at main rate | £150,000 × 25% | £37,500 |
| 3. Upper limit | £250,000 | - |
| 4. Difference | £250,000 - £150,000 | £100,000 |
| 5. Marginal relief | 3/200 × £100,000 | £1,500 |
| 6. Box 440 | £37,500 - £1,500 | £36,000 |
Associated Companies and Thresholds
If you have associated companies, the thresholds are reduced:
| Associates | Lower Limit | Upper Limit |
|---|---|---|
| 0 | £50,000 | £250,000 |
| 1 | £25,000 | £125,000 |
| 2 | £16,667 | £83,333 |
| 3 | £12,500 | £62,500 |
- Profits: £100,000
- Upper limit: £125,000
- Now in marginal band (different calculation)
- Tax may be higher than without associate
Short Accounting Periods
If your accounting period is less than 12 months, thresholds are proportionally reduced:
| Period | Lower Limit | Upper Limit |
|---|---|---|
| 12 months | £50,000 | £250,000 |
| 9 months | £37,500 | £187,500 |
| 6 months | £25,000 | £125,000 |
What Box 440 Includes
Includes
- Tax on trading profits
- Tax on property income
- Tax on non-trading loan relationships
- Tax on chargeable gains
Does Not Include
- VAT (separate tax)
- PAYE (employment tax)
- NIC (National Insurance)
- Interest on late payment
- Penalties
Related CT600 Boxes
Box 440 comes from earlier calculations:
| Box | Description | Feeds Into |
|---|---|---|
| 410 | Taxable total profits | Basis for tax calc |
| 420 | Associated companies | Affects thresholds |
| 430 | Tax at main rate | Before relief |
| 435 | Tax at small rate | If applicable |
| 450 | Marginal relief | Deducted from tax |
Common Mistakes
1. Wrong Rate Applied
Wrong: Using 19% on £200,000 profit Right: 25% minus marginal relief for profits £50k-£250k
2. Forgetting Associated Companies
Wrong: Using £50,000 threshold with associated company Right: Divide thresholds by number of associates + 1
3. Short Period Not Adjusted
Wrong: Using full thresholds for 6-month period Right: Pro-rate thresholds for short periods
4. Manual Calculation Errors
Wrong: Incorrectly applying marginal relief formula Right: Use software or HMRC calculator to verify
When Box 440 Is Zero
Your company may have no tax payable if:
- Profits are nil or negative (loss-making)
- Losses brought forward offset all profits
- Qualifying donations exceed profits
- Special reliefs eliminate tax
Payment Deadline
The tax shown in Box 440 is due:
Normal companies: 9 months and 1 day after accounting period end
Example:
- Period end: 31 March 2025
- Payment due: 1 January 2026
Using TinyTax
TinyTax calculates Box 440 automatically:
- Enter your profit figures
- Confirm associated companies
- We apply correct rates
- Marginal relief calculated if needed
- Box 440 shows your tax due
Verification Checklist
Before submitting, verify:
- Correct tax rate applied for profit level
- Associated companies counted correctly
- Short period thresholds adjusted
- Marginal relief calculated if applicable
- Figure matches your computation
- Payment deadline noted
TinyTax automatically calculates Corporation Tax with marginal relief. Start your CT600 filing